Most people know what reinforced concrete is. It is the usual mix of cement, sand, aggregates, and rebar that is reinforcing it. So what is glass fiber reinforced concrete (GFRC) then?
In GFRC, fiberglass reinforcement for concrete is used in place of regular rebar. You might be wondering what’s the catch here, can’t everything be build with GFRC then? That would save us from the corrosion of rebar.
Apparently, it cannot be. The glass fibers suffer when you mix them with aggregates, but they still have their uses in decorative buildings. You can think of concrete ornaments and things like concrete countertops where adding rebar might be troublesome if you aim for the light product.
GFRC can be cast in ways that we wouldn’t want to try adding rebar into. Like casting thin concrete sinks that are lightweight, the rebar doesn’t have a place in those. Even more when the structure gets more complex.
Glass fiber for concrete
So what does the glass fiber do in the concrete? It adds tensile reinforcement. Rebar only adds it to the directions it is placed. Think about pulling rebar so much it splits. Now the glass fiber is doing that in every direction as it’s mixed with the concrete.
Obviously, it’s not as strong as rebar, but GFRC concrete can be used in other ways than building a concrete slab out of it. For example, it will make good concrete for repairment as adding more rebar when you repair is sometimes troublesome.
GFRC weight might not be that much lower than regular concrete, but if you compare it with thickness it can be half of the regular concrete with glass fiber being the reinforcement. If you think it like that, It can weigh half or less of equal size concrete cast.
Glass fiber reinforced concrete mix
Glass fiber reinforced concrete mix ratio can change a little bit from person to person and of course, there are ready mixes that can be used. GFRC is made from cement, sand, alkaline-resistant glass fiber, and polymer (liquid or dry) so we need to know a little about the ratios.
Notice how rough aggregates aren’t on the list like with concrete. Those aren’t needed here and they could end up damaging the fiber while mixing.
Now the really rough mix would be a 1:1 ratio of sand and cement. Then we would need to add water and liquid polymer that is around 40% of the weight of the cement or a little under. The polymer would make about 40-45% of the weight of the water-polymer mix.
Finally, the glass fiber itself is around 5% of the weight of the cement. Now, remember these are rough estimates for a DIY product. If you build something I’d test different mixes first to find the perfect one with the materials I have at hand.
Glass fibre reinforced concrete suppliers
We scratched the surface of making GFRC ourselves, but that might not be for everyone. For that reason, I’ll add here that you should be able to get GFRC from your local hardware store.
It’s not exactly a new thing as fiber has been used to strengthen structures long before concrete was invented so there should be this kind of concrete products available almost everywhere. You just need to know what to ask for.
Also, you can search the internet and order from there. Reinforcing fibers are available online so for a DIY concrete worker, I’d say give making it a try. Just buy liquid polymer, masonry sand, and cement with that.
Glass fiber reinforced concrete price
What does GFRC cost then? If you’re a DIY concrete crafter it might interest you. Glass fiber is quite affordable really, it only costs about $3.50 per sq foot for the 1-inch thick piece.
When you compare that with concrete it’s obviously a lot more when concrete slab cost starts from $4 per sq foot while being a lot thicker, but we have to think about the projects here.
If GFRC can be half of the regular concrete thickness when used for concrete crafts, it isn’t that much more expensive anymore. When you add the positives of lighter weight and being easier to cast it is even more sensible to use it.
Glass fiber reinforced concrete advantages and disadvantages
At last, I wanted to give GFRC some fair comparison. It’s clear that for making decorations and furniture, it rocks for its light weight.
So for the advantages of GFRC, that’s a big one. It also has high flexural strength (4000 psi) and obviously, it won’t rust like rebar so in bathrooms and kitchens it’s good. Even more so with how easy to cast it is.
One strong point is also that you don’t need any expensive equipment to make GFRC. It is also quite environment friendly.
For disadvantages of GFRC it can be said that it will cost more than concrete with fiber and polymer added, but to give it an honest comparison is difficult as you might need less GFRC for making the same thing with reinforced concrete.
GFRC loses its strength over a long period of time which might be a negative. Before alkaline-resistant fibers, this problem was bigger than it is now. That being said, GFRC should still last pretty much as long as regular reinforced concrete so it shouldn’t be a big problem.
I hope this answers what is glass fiber reinforced concrete and how to use it. I don’t mean to sell it over regular concrete as both have their own uses, but for furniture, it’s something I’ve long since wanted to try.
Homemade furniture seems like something fun to make and there is a lot of woodcrafts all over the internet. Concrete might get a little shadowed.
There are lots of bathroom equipment being made a thought, from countertops and tables to sinks which is quite inspiring. It’s an area where concrete really shines compared to other materials.
The best part is that concrete is easy to cast and lightweight products like this would be easy to install on the walls etc. If you seal the surface well, you wouldn’t have to worry about concretes porous nature either.